A two-degree-of-freedom aeroelasticity experimental device

Abstract

The present invention relates to the field of wind tunnel testing of large wind turbine blades and aircraft wings, and specifically to a two-degree-of-freedom aeroelasticity experimental device, comprising a wind tunnel test model, a two-degree-of-freedom support mechanism, and a signal acquisition system; the wind tunnel test model comprises a wing section model, a pressure measuring tube, an end plate, a central torsion shaft, a locking mechanism, and a center of mass adjustment mechanism; the two-degree-of-freedom support mechanism comprises a wind tunnel fixing plate, a wind tunnel anti-spoiler cover, a support plate, a linear bracket, an angular displacement sensor fixing flange, a torsion shaft fixing rod, a torsion support rod, a smooth linear straight rod, a sinking and buoying elastic mechanism, a pitch linear spring, a pitch spring connecting column, a linear sliding bearing, an outer spherical bearing, a sinking and buoying limit device, and a pitching limit device. The present invention can be used to study the aeroelastic characteristics of a wind tunnel test model under two-degree-of-freedom support conditions of pitch and sinking, that is, to provide an experimental device for exploring phenomena such as flow separation on the wing section surface, dynamic stall, and flutter during aeroelasticity testing.

Description

Technical Field

[0001] The invention relates to the field of wind tunnel tests for large wind turbine blades and aviation wings, and in particular to a two-degree-of-freedom aeroelasticity experimental device. Background Art

[0002] Wind turbine blades are becoming increasingly larger and more flexible, leading to the emergence of high-aspect-ratio blades. Aircraft wings also have high aspect ratios. These high-aspect-ratio blades and wings face numerous challenges caused by nonlinear aeroelasticity, such as flutter.

[0003] Taking the flutter test of wind turbine blades as an example, there are many factors that affect blade flutter, mainly including the structural dynamic parameters of the rotor blades, the characteristics of the incoming flow, and the aerodynamic forces acting on the rotor blades. In the test, the movement of the wing segment with two degrees of freedom is often involved. In addition, flow separation will occur on the surface of the wing segment when flutter occurs. From the perspective of structural fatigue, predicting the vibration frequency and amplitude of the pitch and heave associated with flutter is a major engineering task. Therefore, it is very necessary to use a two-degree-of-freedom aeroelastic experimental device in wind tunnel tests to explore the fluid-structure coupling mechanical characteristics of the blades.

[0004] The aeroelastic models currently used in experiments all feature a fixed-center-of-mass wing section, and the aerodynamic characteristics of the wing section surface are measured using a number of micro-pressure sensors arranged on the airfoil. However, this model is limited to a single center-of-mass location, and the placement of the micro-pressure sensors on the wing section surface is complex. Furthermore, the protrusions of the pressure sensors on the wing section surface can affect the aerodynamic characteristics near the wing section.

[0005] In addition, the aeroelastic model currently designed in the experiment requires the entire device to be placed in the wind tunnel. This will not only increase the blocking effect of the wind tunnel, but more importantly, it will also affect the overall aerodynamic characteristics of the wing section because the supporting structure is exposed to the wind tunnel. Summary of the Invention

[0006] To solve the above problems, the present invention provides a two-degree-of-freedom aeroelastic experimental device, which can be used to study the aeroelastic characteristics of wind tunnel experimental models under the two-degree-of-freedom support conditions of pitch and buoyancy. That is, it is an experimental device for exploring the flow separation on the wing surface and dynamic stall, flutter and other phenomena when conducting aeroelastic tests.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A two-degree-of-freedom aeroelasticity experimental device, comprising a wind tunnel experimental model, a two-degree-of-freedom support mechanism, and a signal acquisition system;

[0009] The wind tunnel test model includes a wing section model, 16 to 28 pressure measuring tubes, two end plates, a set of central torsion shafts, a set of locking mechanisms, and a set of center of mass adjustment mechanisms;

[0010] The wing section model is manufactured by 3D printing. A through hole for placing bolts is designed inside the wing section model. 8 to 14 pressure measuring holes with a diameter of 1.6 mm are designed on the upper and lower surfaces of the wing section model at the mid-span position. The 8 to 14 pressure measuring holes are all along the normal direction of the airfoil surface. The pressure measuring holes are connected to the pressure measuring tube through the air flow channel designed inside the wing section model. The pressure measuring tube extends outside the wind tunnel and is connected to the pressure transmitter.

[0011] The two end plates are manufactured by 3D printing and have a hollow design with the same shape as the hollow cross-section of the wing segment model. They are connected to both ends of the wing segment model through a locking mechanism to prevent the end effect of the wing segment and ensure that the flow is quasi-two-dimensional.

[0012] The central torsion shaft comprises a high-strength torsion shaft bolt, a torsion shaft anti-loosening nut, and an anti-slip sheet. The high-strength torsion shaft bolt passes through the anti-slip sheet, two end plates, and a through-hole reserved for placing bolts inside the wing section model, and is connected to the torsion shaft fixing rod on the two-degree-of-freedom support mechanism and is fixed with the torsion shaft anti-loosening nut. A portion of the anti-slip sheet is embedded in the end plate on the side away from the support mechanism and is fixedly connected to the head of the high-strength torsion shaft bolt to prevent relative sliding between the central torsion shaft and the wing section model.

[0013] The locking mechanism is located near the trailing edge of the wing panel model and includes a fixing bolt and a locking nut. The fixing bolt connects the wing panel model and the two end panels through the through holes reserved for the bolts in the end panels and the wing panel model, and is fixed with the locking nut.

[0014] The described set of center of mass adjustment mechanism includes two conventional mass blocks, two eccentric mass blocks and a set of mass block fixing mechanism; the two conventional mass blocks are made of brass with a hole punched in the center, and the two eccentric mass blocks are made of brass with an eccentric hole punched, and the weight of the eccentric mass blocks is the same as that of the conventional mass blocks; the two conventional mass blocks are used in combination to adjust the center of mass position of the wing section model so that it is closer to the center of the torsion axis, so that the wing section model forms a three-center relative position relationship of the aerodynamic center-torsion axis center (center of gravity) from the leading edge to the trailing edge; the two eccentric mass blocks are used in combination to adjust the center of mass position of the wing section model so that it is closer to the leading edge of the wing section model, so that the wing section model forms a three-center relative position relationship of the aerodynamic center-torsion axis center (center of gravity) from the leading edge to the trailing edge The three-center relative position relationship of aerodynamic center, center of gravity and torsional axis center is formed from the leading edge to the trailing edge; a conventional mass block is used in combination with an eccentric mass block to adjust the center of mass position of the wing section model so that it is closer to the trailing edge of the wing section model, so that the wing section model forms a three-center relative position relationship of aerodynamic center, torsional axis center and center of gravity from the leading edge to the trailing edge; a set of mass block fixing mechanism is composed of mass block fixing bolts and mass block anti-loosening nuts. According to the requirements of different center of mass positions in the test, the two mass blocks are fixed to the end plates on both sides of the wing section model by using the mass block fixing bolts and mass block anti-loosening nuts, thereby realizing the change of the center of mass position of the wing section model;

[0015] The two-degree-of-freedom support mechanism includes a wind tunnel fixing plate, a wind tunnel anti-spoiler cover, two support plates, two linear brackets, an angular displacement sensor fixing flange, a torsion axis fixing rod, two torsion support rods, four smooth linear straight rods, four sets of sinking and buoying elastic mechanisms, four sets of pitching linear springs, eight pitching spring connecting columns, eight linear sliding bearings, two outer spherical bearings, four sets of sinking and buoying limit devices, and eight sets of pitching limit devices.

[0016] The signal acquisition system includes 16 to 28 pressure transmitters, an angular displacement sensor, a non-contact magnetostrictive displacement sensor, and a multi-channel data acquisition and analysis system. The pressure measuring ends of the 16 to 28 pressure transmitters are respectively connected to pressure measuring tubes led out of the wind tunnel, and the other ends are respectively connected to the signal acquisition channels of the multi-channel data acquisition instrument via strain signal input lines. The angular displacement sensor is fixed to the angular displacement sensor fixing flange and further connected to the matching shaft hole of the torsion shaft fixing rod. The signal output end of the angular displacement sensor is connected to the signal acquisition channel of the multi-channel data acquisition instrument via the strain signal input line, and is used to collect the instantaneous pitch angle signal of the wind tunnel test model. The non-contact magnetostrictive displacement sensor is connected to the wind tunnel fixing plate and is 2 mm away from the floating magnet fixed on the linear bracket. The up and down movement of the wind tunnel test model drives the linear movement of the linear bracket and thus drives the linear movement of the floating magnet. The instantaneous heaving and floating displacement of the wind tunnel test model is measured by the distance the floating magnet slides on the measuring rod of the non-contact magnetostrictive displacement sensor. The signal output end of the non-contact magnetostrictive displacement sensor is connected to the signal acquisition channel of the multi-channel data acquisition instrument through a strain signal input line, which is used to collect the instantaneous sinking and floating displacement signal of the wind tunnel test model.

[0017] As a further design of this scheme, eight sets of pitch limit devices are used to limit the large displacement phenomenon that occurs in the pitch motion of the wind tunnel test model, so as to prevent excessive pitch displacement from damaging the two-degree-of-freedom support mechanism and the sensor system; each set of pitch limit devices is composed of a pitch limit device metal fixing plate, four pitch limit device metal fixing plate connecting bolts, a pitch limit device rubber brake block, and two pitch limit device countersunk connecting bolts and two pitch limit device countersunk connecting bolt matching nuts, among which the eight pitch limit device metal fixing plates are respectively fixed to the two linear brackets through thirty-two pitch limit device metal fixing plate connecting bolts, and then the sixteen pitch limit device countersunk connecting bolts respectively pass through the eight pitch limit device rubber brake blocks and are fixed to the eight pitch limit device metal fixing plates through the sixteen pitch limit device countersunk connecting bolts and matching nuts.

[0018] As a further design feature of this solution, the inlet of the air duct inside the wing model is smoothly connected to the pressure tap, while the outlet is located at the end of the wing model on the side with the support structure. A pressure gauge is inserted through the outlet of the air duct at the end of the wing model, and the pressure on the wing model surface is then output to a pressure transmitter located outside the wind tunnel. Both the pressure tap and the air duct were designed with high precision using modeling software, and 3D printing technology also ensures the machining accuracy of the physical wing model.

[0019] As a further design of this solution, the pressure measuring tube is connected to the air flow channel inside the wing section model through one end and sealed with sealant at the interface, and the other end is connected to the pressure measuring end of the pressure transmitter outside the wind tunnel, thereby realizing the measurement of the surface pressure of the wing section model.

[0020] As a further design of this solution, anti-slip grooves are provided at the contact positions between the eccentric mass block and the end plate to prevent the eccentric mass block from sliding relative to the end plate during the movement of the wing section model.

[0021] As a further design of this scheme, the wind tunnel fixing plate is used to fix two support plates, the wind tunnel anti-spoiler cover and the non-contact magnetostrictive displacement sensor, and the wind tunnel fixing plate is fixed to the side wall of the closed section of the wind tunnel by the wind tunnel fixing plate fixing bolts; the wind tunnel anti-spoiler cover is fixed to the wind tunnel fixing plate by the wind tunnel fixing plate fixing bolts, which covers the two-degree-of-freedom support mechanism outside the wind tunnel inside the wind tunnel anti-spoiler cover to prevent the wind tunnel side wall opening from affecting the airflow inside the wind tunnel; the two support plates include an upper support plate and a lower support plate, which are respectively fixed to the wind tunnel fixing plate by support plate fixing bolts, and the upper support plate and the lower support plate are both provided with bolt holes for fixing the sinking and floating limit device and grooves for fixing the sinking and floating elastic mechanism, and the upper support plate is also provided with a bolt hole for connecting the smooth linear straight rod, and the two surfaces of the lower support plate are respectively provided with countersunk bolt holes and cylindrical grooves for connecting the smooth linear straight rod.

[0022] As a further design of this solution, the two linear brackets include an inner linear bracket and an outer linear bracket, both of which are provided with through holes for penetrating the smooth linear straight rod and the torsion shaft fixing rod, as well as grooves for fixing the outer spherical bearing, the linear sliding bearing and the sinking and floating elastic mechanism. In addition, there are bolt holes for fixing the pitch spring connecting column and the pitch limit device, and the outer linear bracket is also provided with a bolt hole for fixing the angular displacement sensor fixing flange; the eight linear sliding bearings and the eight sinking and floating linear spring fixing seats are fixed on the linear bracket by the sinking and floating elastic mechanism fixing bolts. In the groove, two linear brackets are suspended between the upper support plate and the lower support plate through four sets of sinking and floating elastic mechanisms respectively; an outer spherical bearing is provided in the middle of each linear bracket, and the torsion axis fixing rod is connected to the linear bracket through the outer spherical bearing. On the two linear brackets, four sets of pitching linear springs are used to connect the eight pitching spring connecting columns to the two torsion support rods to provide the pitching restoring torque of the wind tunnel test model. The side of the inner linear bracket is also installed with a floating magnet used in conjunction with a non-contact magnetostrictive displacement sensor to collect the sinking and floating motion data of the wind tunnel test model in real time.

[0023] As a further design of this solution, the angular displacement sensor fixing flange is fixed on the outer linear bracket, which fixes the angular displacement sensor to the linear bracket and the torsion axis fixing rod, thereby realizing the measurement of the pitch motion of the wind tunnel test model while the wind tunnel test model is performing sinking and floating motions; a torsion axis fixing clamp is provided at one end of the torsion axis fixing rod, and a connecting port matching the angular displacement sensor is provided at the other end, which is respectively connected to the two linear brackets through two outer spherical bearings; the torsion support rod vertically passes through the torsion axis fixing rod and is fixed to the torsion axis fixing rod by a torsion support rod fixing bolt, and the two torsion support rods and the eight pitch spring connecting columns are connected by four sets of pitch linear springs. Used to convert the pitch motion of the wind tunnel test model into the linear motion of the pitch linear springs. Four smooth linear rods, each with a threaded end and a bolt hole at the other, pass through four sets of buoyancy mechanisms, eight linear bearings, and two inner and outer linear brackets, connecting to the upper and lower support plates. The four buoyancy mechanisms consist of eight buoyancy linear springs, sixteen buoyancy linear spring mounts, sixty-four U-bolts, and sixty-four matching nuts. Each buoyancy mechanism uses eight U-bolts and eight matching nuts to secure the ends of a single buoyancy linear spring to its two mountings. All eight buoyancy linear springs in the four buoyancy mechanisms are preloaded tension springs. One end of the sinking and floating elastic mechanism is connected to the support plate through the sinking and floating elastic mechanism fixing bolts, and the other end is connected to the linear bracket through the sinking and floating elastic mechanism fixing bolts. The upper and lower sinking and floating elastic mechanisms are combined into a group, and a linear bracket is suspended by the two groups of sinking and floating elastic mechanisms. Then, the linear bracket and the wind tunnel test model connected to the linear bracket are suspended between the upper and lower support plates, so that when the wind tunnel test model is subjected to the force of the airflow in the wind tunnel and performs sinking and floating movements in the upper and lower directions, a restoring force is provided for the wind tunnel test model during the sinking and floating movements.The four groups of pitch linear springs use preloaded extension springs, with two pitch linear springs located on both sides of the torsion support rod on one side of the linear bracket as a group. One end is fixed to the pitch spring connecting column, and the other end is fixed to the torsion support rod passing through the torsion axis fixing rod to provide torsional restoring torque for the wind tunnel test model during the pitching motion. The eight pitch spring connecting columns are connected by threads and fixed on the two linear brackets to fix the four groups of pitch linear springs; the eight linear sliding bearings are respectively connected to the sinking and buoyancy linear spring fixing seats at one end of the four groups of sinking and buoyancy elastic mechanisms, and the sinking and buoyancy elastic mechanism is connected to the sinking and buoyancy elastic mechanism with a linear sliding bearing at one end by using the sinking and buoyancy elastic mechanism fixing bolts. The floating linear spring fixing seat is fixed in the grooves set on the inner and outer linear brackets, thereby realizing the fixed connection between the linear sliding bearing and the linear bracket. The eight linear sliding bearings are respectively fixed in the grooves at the connection between the smooth linear straight rod and the linear bracket to reduce the friction of the wind tunnel test model during the sinking and floating movement; the two outer spherical bearings are respectively fixed at the connection between the torsion axis fixing rod and the linear bracket to reduce the friction of the wind tunnel test model during the pitching movement; the four sets of sinking and floating limit devices are used to limit the large displacement phenomenon of the wind tunnel test model during the sinking and floating movement to prevent excessive sinking and floating displacement from damaging the two-degree-of-freedom support mechanism and the sensor system. Each set of sinking and floating limit device is composed of two sinking and floating limit device metal support columns, a sinking and floating limit device metal gasket, a sinking and floating limit device rubber brake block and two sinking and floating limit device countersunk connecting bolts; among them, one end of the sinking and floating limit device metal support column is provided with a thread, and the other end is provided with a bolt hole. The eight sinking and floating limit device metal support columns are respectively connected to the upper and lower support plates, and then the eight sinking and floating limit device countersunk connecting bolts pass through the four sinking and floating limit device rubber brake blocks and the four sinking and floating limit device metal gaskets and are connected to the bolt holes on one side of the eight sinking and floating limit device metal support columns.

[0024] As a further design of this solution, the multi-channel data acquisition and analysis system includes: 18 to 30 strain signal input lines, a multi-channel data acquisition instrument, and a PC-side signal analysis system. The 18 to 30 strain signal input lines respectively connect the sensor output end with the signal input end of the multi-channel data acquisition instrument to transmit the electrical signals collected by the sensor.

[0025] As a further design of this solution, a multi-channel data acquisition instrument is used to collect the electrical signals output by the sensor during the test. It is connected to the PC-side signal analysis system to convert the electrical signals into identifiable physical quantities to be measured. The PC-side signal analysis system is used to analyze and process the electrical signals collected by the multi-channel data acquisition instrument, so that the user can process and analyze the collected physical quantities to be measured in real time.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1) The present invention realizes the change of the center of mass position of the wing section model relative to the center of the torsion axis through the design of the center of mass adjustment mechanism, thereby facilitating the investigation of the influence of the structural characteristics of the wing section on its aerodynamic characteristics and vibration characteristics, and can meet the research needs of the wind tunnel test model at different center of mass positions.

[0028] 2) The present invention adopts the design of an air flow channel wing section model surface pressure measurement system, which realizes the pressure measurement at the mid-span position of the wing section model surface without protrusions on the wing section model surface and without affecting the flow field in the measured area.

[0029] 3) The design of the anti-slip sheet in the central torsion shaft designed in the present invention can effectively prevent relative sliding between the wing section model and the central torsion shaft, thereby reducing the systematic error in the test.

[0030] 4) The two-degree-of-freedom aeroelasticity experimental device designed in the present invention can place the support mechanism and motion measurement mechanism of the wind tunnel experimental model outside the wind tunnel, which can reduce the wind tunnel blockage ratio while reducing the impact of objects other than the wing section on the test results.

[0031] 5) The two-degree-of-freedom support mechanism designed in the present invention can minimize the mechanical friction during the vibration of the wind tunnel test model, thereby reducing the system error that occurs in the test, because a linear sliding bearing is added to the heave degree of freedom and an outer spherical bearing is added to the pitch degree of freedom.

[0032] 6) The torsion axis fixing fixture at one end of the torsion axis fixing rod designed in the present invention can arbitrarily adjust the angle of attack of the wind tunnel test model when there is no wind in the wind tunnel, and can provide a variety of initial working conditions for experimental research.

[0033] 7) The pitch and sink / float limit devices designed in the present invention can effectively prevent damage to the two-degree-of-freedom support mechanism and the sensor system when the wind tunnel test model vibrates with large amplitude.

[0034] 8) The two-degree-of-freedom support mechanism designed in the present invention can effectively decouple the pitch-and-sink degrees of freedom. At the same time, when the wind tunnel test model experiences large-amplitude sinking and floating vibrations, since the sinking and floating linear spring is restricted to a smooth linear straight rod, there will be no obvious lateral tilt of the sinking and floating linear spring, thereby ensuring the linear change of the geometric stiffness of the sinking and floating linear spring. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0036] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0037] Figure 2 Schematic diagram of the structure of the wind tunnel test model of the present invention;

[0038] Figure 3 It is a structural schematic diagram of the two-degree-of-freedom support mechanism of the present invention;

[0039] Figure 4 This is a schematic diagram showing the relative position relationship of the three centers of the wing section model, namely, the aerodynamic center, the torsional axis center (center of gravity), formed from the leading edge to the trailing edge by adjusting the center of mass position of the wind tunnel test model of the present invention through the center of mass adjustment mechanism;

[0040] Figure 5 This is a schematic diagram of the relative position relationship of the aerodynamic center, center of gravity, and torsional axis center formed from the leading edge to the trailing edge of the wing section model by adjusting the center of mass position of the wing section model through the center of mass adjustment mechanism of the wind tunnel test model of the present invention;

[0041] Figure 6 This is a schematic diagram of the wind tunnel test model of the present invention, in which the center of mass position is adjusted by the center of mass adjustment mechanism so that the wing section model forms a relative position relationship of the aerodynamic center, the torsional axis center, and the center of gravity from the leading edge to the trailing edge;

[0042] Figure 7 This is a schematic diagram of the connection of the wing section model of the present invention to the pressure measuring tube;

[0043] Figure 8 Schematic diagram of the air flow path of the wing section model cross section of the present invention;

[0044] Figure 9 is a schematic diagram of a conventional mass block of the present invention;

[0045] Figure 10 is a schematic diagram of an eccentric mass block of the present invention;

[0046] Figure 11 It is a partial schematic diagram of the two-degree-of-freedom support mechanism of the present invention;

[0047] Figure 12 This is a schematic diagram of the connection between the sinking and buoyant elastic mechanism, the support plate and the linear bracket of the present invention;

[0048] Figure 13 Schematic diagram of the connection between the wind tunnel test model and the two-degree-of-freedom support mechanism of the present invention;

[0049] Figure 14 Schematic diagram of the sinking and floating limiting device of the present invention;

[0050] Figure 15 Schematic diagram of the pitch limiting device of the present invention;

[0051] Figure 16It is a schematic diagram of the sinking and floating elastic mechanism of the present invention.

[0052] In the figure, 1- wind tunnel anti-spoiler cover, 2- multi-channel data acquisition instrument, 3- PC-side signal analysis system, 4- pressure transmitter, 5- strain signal input line, 6- pressure measuring tube, 7- dedicated network cable for multi-channel data acquisition instrument, 8- wind tunnel, 9- wing section model, 10- end plate, 11- pressure measuring hole, 12- through hole for placing bolts, 13- high-strength torsion shaft bolt, 14- anti-slip sheet, 15- torsion shaft lock nut, 16- fixing bolt, 17- lock nut, 18- mass block Fixing bolt, 19-mass block anti-loosening nut, 20-conventional mass block, 21-eccentric mass block, 22-air flow channel, 23-wind tunnel fixing plate, 24-support plate, 25-linear bracket, 26-sinking and floating limit device, 27-pitch limit device, 28-angular displacement sensor fixing flange, 29-angular displacement sensor, 30-non-contact magnetostrictive displacement sensor, 31-floating magnet, 32-sinking and floating elastic mechanism, 33-sinking and floating linear spring, 34-sinking and floating linear spring Spring fixing seat, 35-U-bolt, 36-U-bolt matching nut, 37-pitch linear spring, 38-torsion support rod, 39-linear sliding bearing, 40-external spherical bearing, 41-torsion axis fixing rod, 42-pitch spring connecting column, 43-smooth linear straight rod, 44-torsion support rod fixing bolt, 45-sinking and floating elastic mechanism fixing bolt, 46-external spherical bearing fixing bolt, 47-floating magnet fixing bolt, 48-torsion axis fixture fixing bolt, 49-support plate Fixing bolts, 50-wind tunnel fixing plate fixing bolts, 51-sinking and floating limit device metal support column, 52-sinking and floating limit device metal gasket, 53-sinking and floating limit device rubber brake block, 54-sinking and floating limit device countersunk connecting bolt, 55-pitch limit device metal fixing plate, 56-pitch limit device metal fixing plate connecting bolt, 57-pitch limit device rubber brake block, 58-pitch limit device countersunk connecting bolt, 59-pitch limit device countersunk connecting bolt and matching nut. DETAILED DESCRIPTION

[0053] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0054] like Figures 1-16 As shown, a two-degree-of-freedom aeroelasticity experimental device according to an embodiment of the present invention includes a wind tunnel experimental model, a two-degree-of-freedom support mechanism, and a signal acquisition system;

[0055] The wind tunnel test model includes a wing section model 9, 16 to 28 pressure measuring tubes 6, two end plates 10, a set of central torsion shafts, a set of locking mechanisms, and a set of center of mass adjustment mechanisms;

[0056] The wing section model 9 is manufactured by 3D printing. A through hole 12 for placing bolts is designed inside the wing section model 9. 8 to 14 pressure measuring holes 11 with a diameter of 1.6 mm are designed on the upper and lower surfaces of the wing section model 9 at the mid-span position. The 8 to 14 pressure measuring holes 11 are all along the normal direction of the airfoil surface. The pressure measuring holes 11 are connected to the pressure measuring tube 6 through the air flow channel 22 designed inside the wing section model 9. The pressure measuring tube 6 extends outside the wind tunnel 8 and is connected to the pressure transmitter 4.

[0057] The two end plates 10 are manufactured by 3D printing and have a hollow design with the same cross-sectional shape as the wing section model 9. They are fixed to both ends of the wing section model 9 by bolts to prevent the end effect of the wing section and ensure that the flow is quasi-two-dimensional flow.

[0058] The central torsion shaft comprises a high-strength torsion shaft bolt 13, a torsion shaft anti-loosening nut 15, and an anti-slip sheet 14. The high-strength torsion shaft bolt 13 passes through the anti-slip sheet 14, the two end plates 10, and the through hole 12 reserved for placing the bolt inside the wing section model 9, and is connected to the torsion shaft fixing rod 41 on the two-degree-of-freedom support mechanism, and is fixed with the torsion shaft anti-loosening nut 15. A portion of the anti-slip sheet 14 is embedded in the end plate on the side away from the support mechanism and is fixedly connected to the head of the high-strength torsion shaft bolt 13 to prevent relative sliding between the high-strength torsion shaft bolt 13 and the wing section model 9.

[0059] The locking mechanism is located near the trailing edge of the wing panel model 9 and includes a fixing bolt 16 and a locking nut 17. The fixing bolt 16 connects the wing panel model 9 and the two end panels 10 together through the through holes 12 reserved for placing bolts inside the end panels 10 and the wing panel model 9, and is fixed with the locking nut 17.

[0060] The described set of center of mass adjustment mechanism includes two conventional mass blocks 20, two eccentric mass blocks 21 and a set of mass block fixing mechanism; the two conventional mass blocks 20 are made of brass with a hole punched in the center, and the two eccentric mass blocks 21 are made of brass with an eccentric hole punched, and the weight of the eccentric mass block 21 is the same as that of the conventional mass block 20; the two conventional mass blocks 20 are used in combination to adjust the center of mass position of the wing section model 9, so that it is closer to the center of the torsion axis, so that the wing section model 9 forms a three-center relative position relationship of the aerodynamic center-torsion axis center (center of gravity) from the leading edge to the trailing edge; the two eccentric mass blocks 21 are used in combination to adjust the center of mass position of the wing section model 9, so that it is closer to the leading edge of the wing section model 9, so that the wing section model 9 forms a three-center relative position relationship of the aerodynamic center-torsion axis center (center of gravity) from the leading edge to the trailing edge. A three-center relative position relationship of aerodynamic center, center of gravity, and torsional axis center is formed from the leading edge to the trailing edge. A conventional mass block 20 and an eccentric mass block 21 are used in combination to adjust the center of mass position of the wing section model 9 so that it is closer to the trailing edge of the wing section model 9, so that the wing section model 9 forms a three-center relative position relationship of aerodynamic center, torsional axis center, and center of gravity from the leading edge to the trailing edge; a set of mass block fixing mechanisms is composed of mass block fixing bolts 18 and mass block anti-loosening nuts 19. According to the requirements of different center of mass positions in the test, the two mass blocks are respectively fixed to the end plates 10 on both sides of the wing section model 9 by using the mass block fixing bolts 18 and the mass block anti-loosening nuts 19, thereby realizing the change of the center of mass position of the wing section model 9;

[0061] The two-degree-of-freedom support mechanism includes a wind tunnel fixing plate 23, a wind tunnel anti-spoiler cover 1, two support plates 24, two linear brackets 25, an angular displacement sensor fixing flange 28, a torsion axis fixing rod 41, two torsion support rods 38, four smooth linear straight rods 43, four sets of sinking and buoying elastic mechanisms 32, four sets of pitching linear springs 37, eight pitching spring connecting columns 42, eight linear sliding bearings 39, two outer spherical bearings 40, four sets of sinking and buoying limit devices 26, and eight sets of pitching limit devices 27.

[0062] The signal acquisition system includes 16 to 28 pressure transmitters 4, an angular displacement sensor 29, a non-contact magnetostrictive displacement sensor 30 and a multi-channel data acquisition and analysis system. The pressure measuring ends of the 16 to 28 pressure transmitters 4 are respectively connected to the pressure measuring tubes 6 drawn from the wind tunnel 8, and the other ends are respectively connected to the signal acquisition channels of the multi-channel data acquisition instrument 2 through the strain signal input lines 5. The angular displacement sensor 29 is fixed on the angular displacement sensor fixing flange 28 and then connected to the matching shaft hole of the torsion shaft fixing rod 41. The signal output of the angular displacement sensor 29 is The end is connected to the signal acquisition channel of the multi-channel data acquisition instrument 2 via a strain signal input line 5, and is used to collect the instantaneous pitch angle signal of the wind tunnel test model. The non-contact magnetostrictive displacement sensor 30 is connected to the wind tunnel fixed plate 23, and its distance from the floating magnet 31 fixed to the linear bracket 25 is 2 mm. The up and down movement of the wind tunnel test model drives the linear movement of the linear bracket 25, which in turn drives the linear movement of the floating magnet 31. The instantaneous heaving and floating displacement of the wind tunnel test model is measured by the distance that the floating magnet 31 slides on the measuring rod of the non-contact magnetostrictive displacement sensor 30. The signal output end of the non-contact magnetostrictive displacement sensor 30 is connected to the signal acquisition channel of the multi-channel data acquisition instrument 2 via a strain signal input line 5, and is used to collect the instantaneous heaving and floating displacement signal of the wind tunnel test model.

[0063] The assembly process includes the following steps: 1. The two-degree-of-freedom support mechanism is assembled. Specifically, the eight sinking and buoyant linear springs 33 are each secured to the sixteen sinking and buoyant linear spring mounting bases 34 using sixty-four U-bolts 35 and sixty-four matching nuts 36, thereby assembling four groups, or eight sinking and buoyant elastic mechanisms 32. It should be noted that the four groups of sinking and buoyant elastic mechanisms 32 consist of two symmetrical sinking and buoyant elastic mechanisms 32 per linear bracket 25, with each linear bracket 25 suspended by two groups of sinking and buoyant elastic mechanisms 32. Then, four sets of sinking and floating limit devices 26 are respectively installed on the upper and lower support plates 24. Each set of sinking and floating limit devices 26 is composed of two sinking and floating limit device metal support columns 51, a sinking and floating limit device metal gasket 52, a sinking and floating limit device rubber brake block 53 and two sinking and floating limit device countersunk connecting bolts 54. Among them, one end of the sinking and floating limit device metal support column 51 is provided with a thread, and the other end is provided with a bolt hole. The eight sinking and floating limit device metal support columns 51 are respectively connected to the upper and lower support plates 24, and then the eight sinking and floating limit device countersunk connecting bolts 54 are respectively passed through the four sinking and floating limit device rubber brake blocks 53 and the four sinking and floating limit device metal gaskets 52 and connected to the bolt holes on one side of the eight sinking and floating limit device metal support columns 51. It should be noted that: two sets of sinking and floating limit devices 26 are installed on each support plate 24, and the sinking and floating limit devices 26 on the upper and lower support plates 24 are arranged symmetrically with each other. Next, connect the threaded ends of the four smooth linear rods 43 to the bolt holes reserved in the upper support plate. The smooth linear rods 43 have threads on one end and bolt holes on the other. The upper support plate also has grooves for securing the buoyancy mechanisms 32. Then, pass the four buoyancy mechanisms 32 through the four smooth linear rods 43, and secure the buoyancy linear spring fixing seats 34 at one end of the four buoyancy mechanisms 32 to the grooves in the upper support plate using the buoyancy mechanism fixing bolts 45.

[0064] Next, the four linear sliding bearings 39 are connected to the other ends of the four sinking and buoying elastic mechanisms 32 connected to the upper support plate through the four smooth linear straight rods 43. The four smooth linear straight rods 43 connected to the upper support plate are then passed through the through-holes provided in the inner and outer linear brackets 25. The sinking and buoying linear spring holders 34 connected to the linear sliding bearings 39 are then secured to the grooves provided above the inner and outer linear brackets 25 using the sinking and buoying elastic mechanism fixing bolts 45. The inner linear bracket mentioned here refers to the linear bracket on the side closer to the wind tunnel fixing plate 23, while the outer linear bracket refers to the linear bracket on the side away from the wind tunnel fixing plate 23.

[0065] Then connect the other four linear sliding bearings 39 to the sinking and floating linear spring fixing seats 34 at one end of the other four sinking and floating elastic mechanisms 32, and then pass the connected sinking and floating elastic mechanisms 32 and linear sliding bearings 39 through the four smooth linear straight rods 43 connected to the upper support plate, and use the sinking and floating elastic mechanism fixing bolts 45 to fix the sinking and floating linear spring fixing seats 34 connected to the linear sliding bearings 39 in the grooves set under the inner and outer linear brackets 25.

[0066] The lower support plate, to which the sinking and floating limiter 26 is fixed, is then mounted on one end of the four smooth linear rods 43 with bolt holes. Four countersunk bolt holes and four cylindrical grooves for connecting the smooth linear rods 43 are provided on both sides of the lower support plate. The four cylindrical grooves on the top of the lower support plate are used to connect the bolt holes at one end of the four smooth linear rods 43, while the four countersunk bolt holes on the bottom of the lower support plate are used to bolt the bolt holes at the bottom ends of the four smooth linear rods 43. Furthermore, a groove for securing the sinking and floating elastic mechanism 32 is also provided on the lower support plate. The sinking and floating linear spring fixing seat 34 at the other end of the four sinking and floating elastic mechanisms 32, which are connected below the inner and outer linear brackets 25, is then secured to the groove on the lower support plate using the sinking and floating elastic mechanism fixing bolts 45.

[0067] The two outer spherical bearings 40 are then secured to the grooves on the outside of the inner and outer linear brackets 25 using outer spherical bearing fixing bolts 46. The outer sides here refer to the side of the inner linear bracket close to the wind tunnel fixing plate 23 and the side of the outer linear bracket away from the wind tunnel fixing plate 23. The torsion shaft fixing rod 41 is then passed through the two outer spherical bearings 40 and fastened to the bearings. The two torsion support rods 38 are then vertically passed through the front and rear reserved through-holes of the torsion shaft fixing rod 41 and secured to the torsion shaft fixing rod 41 using torsion support rod fixing bolts 44. The front and rear reserved through-holes of the torsion shaft fixing rod 41 are located at the same distance from the outer side surfaces of the inner and outer linear brackets 25. Four sets of eight pitch spring connecting columns 42 are then threadedly mounted on the outsides of the inner and outer linear brackets 25. Two symmetrical pitch spring connecting columns 42 on one side of each linear bracket 25 form a group. Each linear bracket 25 has two sets of pitch spring connecting columns 42 symmetrically mounted about the cross-sectional center of the torsion axis fixing rod 41. Four sets of pitch linear springs 37 connect the four sets of pitch spring connecting columns 42 to the two torsion struts 38. Two symmetrical pitch linear springs 37 on one side of each linear bracket 25 form a group. Each linear bracket 25 has two sets of pitch linear springs 37 mounted on it. Next, eight sets of pitch limiters 27 are installed on the inner and outer linear brackets 25, respectively. Four sets of pitch limiters 27 are mounted on the outer sides of each linear bracket 25, with two sets forming a symmetrical group mounted on either side of the torsion support rod 38. The two sets of pitch limiters 27 on each linear bracket 25 are symmetrical about the cross-sectional center of the torsion axis fixing rod 41. Each set of pitch limiters 27 consists of a pitch limiter metal fixing plate 55, four pitch limiter metal fixing plate connecting bolts 56, a pitch limiter rubber brake block 57, two pitch limiter countersunk connecting bolts 58, and two pitch limiter countersunk connecting bolt nuts 59. Here, the installation of a pitch limiter 27 is described as an example: a pitch limiter metal fixing plate 55 is secured to a linear bracket 25 via four pitch limiter metal fixing plate connecting bolts 56. Then, two pitch limiter countersunk connecting bolts 58 pass through a pitch limiter rubber brake block 57 and are secured to the pitch limiter metal fixing plate 55 via two pitch limiter countersunk connecting bolts and nuts 59. Next, the angular displacement sensor fixing flange 28 is secured to the angular displacement sensor 29 using bolts. Finally, the angular displacement sensor fixing flange 28, with the angular displacement sensor 29 secured thereto, is bolted to the outer linear bracket.Then, the floating magnet 31 used in conjunction with the non-contact magnetostrictive displacement sensor 30 is fixed to the inner linear bracket with the floating magnet fixing bolt 47, and then the non-contact magnetostrictive displacement sensor 30 is fixed to the wind tunnel fixing plate 23 with bolts, and then the assembled upper and lower support plates 24 are fixed to the wind tunnel fixing plate 23 with support plate fixing bolts 49, and then the wind tunnel anti-spoiler cover 1 is connected to the wind tunnel fixing plate 23 through the wind tunnel fixing plate fixing bolts 50, and then the overall two-degree-of-freedom support mechanism is fixed to the outer wall of the wind tunnel 8 with the wind tunnel fixing plate fixing bolts 50.

[0068] The wind tunnel test model is then assembled. Specifically, the pressure measuring tube 6 is first connected to the air flow channel 22 inside the wing section model 9, and then the interface between the air flow channel 22 of the wing section model 9 and the pressure measuring tube 6 is sealed with sealant. Ten pressure measuring holes 11 with a diameter of 1.6 mm are designed with high precision on the upper and lower surfaces at the mid-span position of the wing section model 9. The designed pressure measuring holes 11 are all along the normal direction of the surface of the wing section model 9, and the pressure measuring holes 11 are connected to the pressure measuring tube 6 through the air flow channel 22 designed inside the wing section model 9. The air flow channel 22 designed inside the wing section model 9 has its inlet end smoothly connected to the pressure measuring hole 11, and the outlet end of the air flow channel 22 is located at the end of the wing section model 9 on the side with the two-degree-of-freedom support mechanism. Then, a set of central torsion shafts and a set of locking mechanisms are used to fix the wing section model 9 and the two end plates 10 together. Two of the end plates 10 have a hollow design that is the same as the hollow shape of the cross section of the wing section model 9, and are fixedly connected to the two ends of the wing section model 9 by bolts to prevent the end effect of the wing section model 9 and ensure that the flow is quasi-two-dimensional flow. The set of central torsion shafts mentioned above includes a high-strength torsion shaft bolt 13, a torsion shaft anti-loosening nut 15, and an anti-slip sheet 14, wherein a portion of the anti-slip sheet 14 is embedded in the end plate on the side away from the support mechanism and is fixedly connected to the head of the high-strength torsion shaft bolt 13 to prevent relative sliding between the high-strength torsion shaft bolt 13 and the wing section model 9. The set of locking mechanisms mentioned above is located near the trailing edge of the wing section model 9 and includes a fixing bolt 16 and an anti-loosening nut 17. The fixing bolt 16 connects the wing section model 9 and the two end plates 10 together through the end plate 10 and the through hole 12 reserved for placing the bolt inside the wing section model 9, and is fixed with an anti-loosening nut 17. Then, the high-strength torsion axis bolt 13 of the connected wind tunnel test model is fixed to one end of the torsion axis fixing fixture of the torsion axis fixing rod 41 on the two-degree-of-freedom support mechanism using the torsion axis clamp fixing bolt 48. Then, the center of mass adjustment mechanism is installed on the wing section model 9, wherein a set of center of mass adjustment mechanism includes two conventional mass blocks 20, two eccentric mass blocks 21, and a set of mass block fixing mechanism. The eccentric mass blocks 21 have the same weight as the conventional mass blocks 20. The eccentric mass blocks 21 are designed with eccentric holes, while the conventional mass blocks 20 are designed with central holes. Both mass blocks are made of brass and are used to adjust the center of mass position of the wing section model 9. A set of mass block fixing mechanism consists of mass block fixing bolts 18 and mass block anti-loosening nuts 19. By using the mass block fixing bolts 18 and mass block anti-loosening nuts 19, the two mass blocks are respectively fixed to the end plates 10 on both sides of the wing section model 9. During the test, the position of the mass blocks can be adjusted according to different center of mass requirements, thereby achieving the effect of changing the center of mass position.

[0069] Finally, the pressure measuring pipeline is connected to the signal acquisition system. Specifically, the other end of the pressure measuring tube 6 connected to the air flow channel 22 of the wing section model 9 is first led out of the wind tunnel 8 and connected to the pressure measuring end of the pressure transmitter 4. Then, the connected pressure measuring channel is checked for air tightness using the pressure transmitter 4 and the multi-channel data acquisition and analysis system. After ensuring that all pressure measuring channels are airtight, the angular displacement sensor 29 and the non-contact magnetostrictive displacement sensor 30 are connected to the multi-channel data acquisition and analysis system. The multi-channel data acquisition and analysis system includes: a strain signal input line 5, a multi-channel data acquisition instrument 2, and a PC-side signal analysis system 3. The strain signal input line 5 mentioned above connects the sensor output end to the signal input end of the multi-channel data acquisition instrument 2 respectively, and then the multi-channel data acquisition instrument 2 is connected to the network cable interface end of the PC through the multi-channel data acquisition instrument dedicated network cable 7. The strain signal input line 5 is used to transmit the signal collected by the sensor, the multi-channel data acquisition instrument 2 is used to collect the electrical signal output by the sensor during the test, and the PC-side signal analysis system 3 is used to analyze and process the electrical signal collected by the multi-channel data acquisition instrument 2, so that the user can process and analyze the collected physical quantity to be measured in real time.

[0070] At this point, all experimental devices designed by the present invention have been installed. The following will further illustrate the connected experimental devices through several embodiments:

[0071] Example 1

[0072] The operation is explained by taking the experimental study on the influence of the center of mass position of the wind turbine wing section model on flutter as an example.

[0073] When the wind tunnel 8 is not blowing, the high-precision digital inclinometer is temporarily fixed to the end plate 10 at one end of the wing section model 9, and then the angle of the high-strength torsion axis bolt 13 relative to the torsion axis fixing fixture at one end of the torsion axis fixing rod 41 is adjusted, and then the real-time inclination angle of the wing section model 9 displayed by the digital inclinometer is used to fix the wing section model 9 at three center of mass positions at the same angle of attack, wherein the adjustment of the three center of mass positions of the wing section model 9 is achieved by adjusting the position of the mass block in the center of mass adjustment mechanism. For a two-degree-of-freedom aerodynamic elasticity experimental device disclosed in the present invention, three bolt through holes for fixing the mass block are set inside the wing section model 9, which respectively correspond to the three center of mass positions of the wing section model 9, namely the aerodynamic center-torsion axis center (center of gravity) (such as Figure 4 As shown); aerodynamic center - center of gravity - torsional axis center (as shown Figure 5 As shown); aerodynamic center - torsional axis center - center of gravity (as shown); Figure 6As shown). At the three center of mass positions, the ratio of the distance x between the center of mass and the center of the torsion axis to the chord length c of the airfoil is 0, +0.0303, and -0.0623, respectively. Then, at different center of mass positions, by gradually increasing the wind tunnel wind speed, the test data is collected using the angular displacement sensor 29, the non-contact magnetostrictive displacement sensor 30, and the pressure transmitter 4. The electrical signal collected by the sensor is then transmitted to the multi-channel data acquisition instrument 2 through the strain signal input line 5. Finally, the electrical signal is analyzed and processed by the PC-side signal analysis system 3 and the multi-channel data acquisition instrument 2, and then converted into the instantaneous pitch angle, instantaneous sinking and floating displacement of the wing section model 9 and the surface pressure signal of the wing section model 9 required to be measured in the test. Then, by observing the vibration conditions of the wing section model 9 at the three center of mass positions, the flutter critical wind speed of the wing section model 9 at the three center of mass positions is determined, and then the pitching, sinking and floating motion data of the wing section model 9 in the limit cycle oscillation state and the pressure signal on its surface are recorded. Finally, by exploring the influence of the center of mass position of the wing section model 9 on the critical flutter speed, the optimal center of mass position of the wing section model 9 is found, and the flutter boundary of the wing section model 9 is controlled.

[0074] Example 2

[0075] The operation is explained by taking the investigation of the bifurcation behavior of the airfoil stall flutter in a low-speed wind tunnel as an example.

[0076] After fixing the center of mass of wing section model 9 by installing a mass block on it, the angle of attack of wing section model 9 is adjusted to a certain angle when the wind tunnel 8 is not blowing. Then, the wind tunnel 8 is opened, and the airflow pressure at the mid-span position of the wing section model 9 is measured using the pressure transmitter 4, the pressure measuring tube 6, the air flow channel 22 inside the wing section model 9, and the pressure measuring hole 11. The pressure signal is then measured, and combined with the instantaneous pitch angle measured by the angular displacement sensor 29, the curves of the lift coefficient and pitching moment coefficient of wing section model 9 over time are obtained. The vibration state of wing section model 9 is also determined by combining the curves of the instantaneous pitch and heave displacement of wing section model 9 over time. When the vibration of wing section model 9 reaches the stall flutter state, the relationship between the limit cycle vibration amplitude of wing section model 9's pitch angle (heave displacement, lift coefficient, and pitching moment coefficient) and the wind tunnel wind speed is recorded. Then, the angle of attack of the wing section model 9 under no wind conditions was changed, and the above experimental steps were repeated. Finally, the relationship between the limit cycle vibration amplitude experienced by the pitch angle (sinking and buoyancy displacement, lift coefficient, and pitching moment coefficient) of multiple groups of wing section models 9 at different angles of attack and the wind tunnel wind speed was obtained, and then the bifurcation behavior experienced by the wing section model 9 during stall flutter was explored.

[0077] Example 3

[0078] The operation is explained using the flow separation phenomenon on the surface of a wing during stall flutter as an example.

[0079] After fixing the center of mass of wing model 9 by attaching a mass block to it, the angle of attack of wing model 9 is adjusted to a certain angle when no air is blowing through wind tunnel 8. Wind tunnel 8 is then opened. When wing model 9 reaches a stall flutter state, the airflow pressure at the mid-span position of wing model 9 is measured using pressure transmitter 4, pressure gauge tube 6, air flow channel 22 within wing model 9, and pressure tap 11. This allows the variation of the pressure coefficients on the upper and lower surfaces of wing model 9 with the chord length of the airfoil at different pitch angles to be studied, thereby analyzing the aerodynamic characteristics of the surface of wing model 9. Furthermore, particle image velocimetry can be used to further investigate the flow separation on the surface of wing model 9. This can then be compared with the pressure variation trend on the surface of wing model 9 measured by pressure transmitter 4, thereby exploring the mechanism of induced stall flutter of wing model 9.

[0080] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A two-degree-of-freedom aeroelasticity experimental device, characterized by: Including wind tunnel test model, two-degree-of-freedom support mechanism, and signal acquisition system; The wind tunnel test model includes a wing section model, 16 to 28 pressure measuring tubes, two end plates, a set of central torsion shafts, a set of locking mechanisms, and a set of center of mass adjustment mechanisms; The wing section model is manufactured by 3D printing. A through hole for placing bolts is designed inside the wing section model. 8 to 14 pressure measuring holes with a diameter of 1.6 mm are designed on the upper and lower surfaces of the wing section model at the mid-span position. The 8 to 14 pressure measuring holes are all along the normal direction of the airfoil surface. The pressure measuring holes are connected to the pressure measuring tube through the air flow channel designed inside the wing section model. The pressure measuring tube extends outside the wind tunnel and is connected to the pressure transmitter. The two end plates are manufactured by 3D printing and have a hollow design with the same shape as the hollow cross-section of the wing segment model. They are connected to both ends of the wing segment model through a locking mechanism to prevent the end effect of the wing segment and ensure that the flow is quasi-two-dimensional. The central torsion shaft comprises a high-strength torsion shaft bolt, a torsion shaft anti-loosening nut, and an anti-slip sheet. The high-strength torsion shaft bolt passes through the anti-slip sheet, two end plates, and a through hole reserved for the bolt inside the wing section model, and is connected to the torsion shaft fixing rod outside the wind tunnel and is fixed with the torsion shaft anti-loosening nut. A portion of the anti-slip sheet is embedded in the end plate on the side away from the support mechanism and is fixedly connected to the head of the high-strength torsion shaft bolt to prevent relative sliding between the central torsion shaft and the wing section model. The locking mechanism is located near the trailing edge of the wing panel model and includes a fixing bolt and a locking nut. The fixing bolt connects the wing panel model and the two end panels through the through holes reserved for the bolts inside the wing panel model and the end panels, and is fixed with the locking nut. The center of mass adjustment mechanism includes a set of conventional mass blocks, a set of eccentric mass blocks and a set of mass block fixing mechanisms; a set of conventional mass blocks includes two conventional mass blocks, the conventional mass blocks are made of brass, and the center is punched, which is used to adjust the center of mass position of the wing section model to be close to the center of the torsion axis, so that the wing section model forms a three-center relative position relationship of the aerodynamic center-torsion axis center (center of gravity) from the leading edge to the trailing edge; a set of eccentric mass blocks includes two eccentric mass blocks, the eccentric mass blocks are made of brass, and the eccentric is punched, which is used to adjust the center of mass position of the wing section model to be closer to the leading edge of the wing section model, so that the wing section model forms an aerodynamic center-torsion axis center (center of gravity) from the leading edge to the trailing edge. The relative position relationship of the three centers of force, center of gravity, and torsional axis center, the eccentric mass block has the same weight as the conventional mass block; a conventional mass block and an eccentric mass block are used in combination to adjust the center of mass position of the wing section model to be close to the trailing edge position of the wing section model, so that the wing section model forms a relative position relationship of the three centers of aerodynamic center, torsional axis center, and center of gravity from the leading edge to the trailing edge; a set of mass block fixing mechanisms consists of mass block fixing bolts and mass block anti-loosening nuts, and the two mass blocks are respectively fixed to the end plates on both sides of the wing section model by using the mass block fixing bolts and mass block anti-loosening nuts, thereby realizing the change of the center of mass position of the wing section model; The two-degree-of-freedom support mechanism includes a wind tunnel fixing plate, a wind tunnel anti-spoiler cover, two support plates, two linear brackets, an angular displacement sensor fixing flange, a torsion axis fixing rod, two torsion support rods, four smooth linear straight rods, four sets of sinking and floating linear springs, four sets of pitching linear springs, eight pitching spring connecting columns, eight linear sliding bearings, two outer spherical bearings, four sets of sinking and floating limit devices, and eight sets of pitching limit devices; The signal acquisition system includes 16 to 28 pressure transmitters, an angular displacement sensor, a non-contact hysteresis and expansion displacement sensor, and a multi-channel data acquisition and analysis system. The pressure measuring ends of the 16 to 28 pressure transmitters are respectively connected to the pressure measuring tubes led out of the wind tunnel, and the other ends are respectively connected to the signal acquisition channels of the multi-channel data acquisition instrument through strain signal input lines. The angular displacement sensor is fixed on the angular displacement sensor fixing flange and then connected to the matching shaft hole of the torsion shaft fixing rod. The signal output end of the angular displacement sensor is connected to the signal acquisition channel of the multi-channel data acquisition instrument through the strain signal input line for collecting The instantaneous pitch angle signal of the wind tunnel test model is obtained by connecting a non-contact magnetostrictive displacement sensor to a wind tunnel fixed plate, with a distance of 2 mm between the sensor and the floating magnet fixed to the linear bracket. The up and down movement of the wind tunnel test model drives the linear movement of the linear bracket, which in turn drives the linear movement of the floating magnet. The instantaneous sinking and floating displacement of the wind tunnel test model is measured by the distance the floating magnet slides on the measuring rod of the non-contact magnetostrictive displacement sensor. The signal output end of the non-contact magnetostrictive displacement sensor is connected to the signal acquisition channel of a multi-channel data acquisition instrument via a strain signal input line to collect the instantaneous sinking and floating displacement signal of the wind tunnel test model.

2. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The inlet end of the air flow channel inside the wing section model is smoothly connected to the pressure measuring hole, and the outlet end of the air flow channel is located at the end of the wing section model on the side where the support mechanism is provided. Then, a pressure measuring tube is inserted into the outlet end of the air flow channel at the end of the wing section model to lead the pressure on the surface of the wing section model to the pressure transmitter located outside the wind tunnel.

3. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The pressure measuring tube is connected to the air flow channel inside the wing section model through one end and sealed with sealant at the interface, and the other end is connected to the pressure measuring end of the pressure transmitter outside the wind tunnel, thereby realizing the measurement of the surface pressure of the wing section model.

4. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: Anti-slip grooves are provided at the contact positions between the eccentric mass block and the end plate to prevent the eccentric mass block from sliding relative to the end plate during the movement of the wing section model.

5. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The wind tunnel fixing plate is used to fix two support plates, a wind tunnel anti-spoiler cover and a non-contact magnetostrictive displacement sensor, and the wind tunnel fixing plate is fixed to the side wall of the closed section of the wind tunnel by means of wind tunnel fixing plate fixing bolts; the wind tunnel anti-spoiler cover is fixed to the wind tunnel fixing plate by means of wind tunnel fixing plate fixing bolts, which covers the two-degree-of-freedom support mechanism outside the wind tunnel inside the wind tunnel anti-spoiler cover, and is used to prevent the wind tunnel side wall opening from affecting the airflow inside the wind tunnel; the two support plates include an upper support plate and a lower support plate, which are respectively fixed to the wind tunnel fixing plate by means of support plate fixing bolts, and the upper support plate and the lower support plate are both provided with bolt holes for fixing the sinking and floating limit devices, and the upper support plate is also provided with a bolt hole for connecting a smooth linear straight rod, and countersunk bolt holes and cylindrical grooves for connecting the smooth linear straight rod are respectively provided on the two surfaces of the lower support plate.

6. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The two linear brackets include an inner linear bracket and an outer linear bracket. Both linear brackets are provided with through holes, grooves for fixing outer spherical bearings and linear sliding bearings, and bolt holes for fixing pitch spring connecting columns and pitch limit devices. The outer linear bracket is also provided with bolt holes for fixing the angular displacement sensor fixing flange. Eight linear sliding bearings are fixed in the grooves of the linear brackets by linear sliding bearing fixing bolts. The two linear brackets are respectively connected to the upper support plate and the lower support plate by four smooth linear straight rods passing through the eight linear sliding bearings and four groups of sinking and floating linear springs. An outer spherical bearing is respectively provided in the middle of the two linear brackets. The torsion axis fixing rod is connected to the linear bracket through the outer spherical bearing. The two linear brackets are respectively connected to the eight pitch spring connecting columns and the torsion support rod through four groups of pitch linear springs to provide the pitch restoring torque of the wing section model. The side of the inner linear bracket is also installed with a floating magnet used in conjunction with the non-contact magnetostrictive displacement sensor to collect the sinking and floating motion data of the wing section model in real time.

7. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: Eight sets of pitch limit devices are used to limit the large displacement phenomenon that occurs during the pitch motion of the wind tunnel test model, so as to prevent excessive pitch displacement from damaging the two-degree-of-freedom support mechanism and the sensor system; each set of pitch limit devices is composed of a pitch limit device metal fixing plate, four pitch limit device metal fixing plate connecting bolts, a pitch limit device rubber brake block, two pitch limit device countersunk connecting bolts and two pitch limit device countersunk connecting bolt matching nuts, among which the eight pitch limit device metal fixing plates are respectively fixed to the two linear brackets through thirty-two pitch limit device metal fixing plate connecting bolts, and then the sixteen pitch limit device countersunk connecting bolts respectively pass through the eight pitch limit device rubber brake blocks and are fixed to the eight pitch limit device metal fixing plates through the sixteen pitch limit device countersunk connecting bolts matching nuts.

8. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The angular displacement sensor fixing flange is fixed on the outer linear bracket. It fixes the angular displacement sensor to the linear bracket and the torsion axis fixing rod together, thereby realizing the measurement of the pitch motion of the wing section model while the wing section model is performing the sinking and floating motion; one end of the torsion axis fixing rod is provided with a torsion axis fixing fixture, and the other end is provided with a connecting port matching the angular displacement sensor, which is respectively connected to the two linear brackets through two outer spherical bearings; the torsion support rod vertically passes through the torsion axis fixing rod and is fixed to the torsion axis fixing rod by a torsion support rod fixing bolt, and the torsion support rod and the pitch spring connecting column are connected by four sets of pitch linear springs respectively, so as to convert the pitch motion of the wing section model into the linear motion of the pitch linear spring. ; One end of the four smooth linear straight rods is provided with a thread and the other end is provided with a bolt hole, which passes through the sinking and floating linear springs and the linear bracket and is connected to the upper and lower support plates respectively; the four groups of sinking and floating linear springs use preloaded tension springs, one end of which is connected to the support plate and the other end is connected to the linear bracket, and the upper and lower sinking and floating linear springs are used as a group, and a linear bracket is suspended by the two groups of sinking and floating linear springs, and then the linear bracket and the wing section model connected to the linear bracket are suspended between the upper and lower support plates, so that when the wing section model is subjected to the force of the airflow in the wind tunnel and performs sinking and floating movements in the upper and lower directions, a restoring force is provided for the wing section model in the sinking and floating movement; the four groups of pitching linear springs use preloaded tension springs, and the linear bracket is used as a group. The two pitch linear springs on both sides of the torsion support rod on one side of the frame form a group, which provide torsional restoring torque for the wing section model during pitch motion by fixing one end on the pitch spring connecting column and the other end on the torsion support rod passing through the torsion axis fixing rod. The four groups of pitch spring connecting columns are connected by threads and fixed on the two linear brackets to fix the four groups of pitch linear springs; eight linear sliding bearings are respectively fixed at the connection between the smooth linear straight rod and the linear bracket to reduce the friction during the sinking and floating motion of the wing section model; two outer spherical bearings are respectively fixed at the connection between the torsion axis fixing rod and the linear bracket to reduce the friction during the pitching motion; four sets of sinking and floating limit devices are used to limit the wind tunnel test model during the sinking and floating motion The large displacement phenomenon that occurs in the vehicle is to prevent the damage of the two-degree-of-freedom support mechanism and the sensor system caused by excessive sinking and floating displacement; each set of sinking and floating limit devices is composed of two sinking and floating limit device metal support columns, a sinking and floating limit device metal gasket, a sinking and floating limit device rubber brake block and two sinking and floating limit device countersunk connecting bolts; wherein, one end of the sinking and floating limit device metal support column is provided with a thread, and the other end is provided with a bolt hole, and the eight sinking and floating limit device metal support columns are respectively connected to the upper and lower support plates, and then the eight sinking and floating limit device countersunk connecting bolts respectively pass through the four sinking and floating limit device rubber brake blocks and the four sinking and floating limit device metal gaskets and are connected to the bolt holes on one side of the eight sinking and floating limit device metal support columns.

9. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The multi-channel data acquisition and analysis system includes: 18 to 30 strain signal input lines, a multi-channel data acquisition instrument, and a PC-side signal analysis system. The 18 to 30 strain signal input lines respectively connect the sensor output end with the signal input end of the multi-channel data acquisition instrument to transmit the sensor acquisition signal.

10. The two-degree-of-freedom aeroelasticity experimental device according to claim 1, characterized in that: The multi-channel data acquisition instrument is used to collect the electrical signals output by the sensor during the test. It is connected to the signal acquisition and analysis system on the PC to convert the electrical signals into identifiable physical quantities to be measured. The PC signal acquisition and analysis system is used to analyze and process the electrical signals collected by the multi-channel data acquisition instrument, so that users can process and analyze the collected physical quantities to be measured in real time.

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